1. Filed of the Invention
The present invention relates to a laser welding method. More specifically, it relates to a novel laser welding method, capable of preventing formation of a welding defect, and achieving a deep penetration by a low heat input so as to enable formation of a welding structure with a high strength and a high toughness even in the case of a high power laser welding.
2. Description of the Related Art
Recently, a higher output of laser oscillators has been promoted dramatically, and application thereof for the deep penetration and the high speed welding is expected. However, for example, as described in FIG. 1, with a deeper penetration, it gets difficult to stably maintain a keyhole. Thereby, defects such as the porosity, the blowhole, and cracking can easily be formed.
This has been a serious problem to establish a high quality welding with a high power CO2 laser.
Although methods for preventing porosity, cracking or spatter in a welded part have been discussed so far as a welding method using an YAG laser, the discussion has been held so far for welding of a thin plate, and thus a method for stably maintaining a keyhole in welding with a high power laser for a deep penetration, capable of effectively preventing formation of defects such as the porosity, the blowhole, and cracking has not been provided so far.
Accordingly, in order to solve the above-mentioned conventional problems, an object of the present invention is to provide a novel laser welding method, capable of preventing formation of a welding defect, and achieving a deep penetration by a low heat input so as to enable formation of a welding structure with a high strength and a high toughness even in the case of a high power laser welding.
In order to solve the above-mentioned problems, a first aspect of the present invention is a laser welding method for welding with a periodical fluctuation adjustment so as to have a base output of 50% or more with respect to a peak output.
Moreover, a second aspect of the present invention is a laser welding method, with a base output of 50 to 70% with respect to a peak output. A third aspect of the present invention is a laser welding method for applying a periodical fluctuation of 200 Hz or less to the output. A fourth aspect of the present invention is a laser welding method with a 10 mm or more penetration depth.
Furthermore, a fifth aspect of the present invention is a method of using a CO2 laser in any of the above-mentioned methods, and a sixth aspect of the present invention is a method of using a high power CO2 laser of 5 KW or more.